1. Field of the Invention
The present invention relates to a smart antenna module and omni-directional antenna thereof, and more particularly, to a smart antenna module and omni-directional antenna thereof having a radiation pattern which is adjusted by adjusting the ground state of at least one reflecting unit.
2. Description of the Prior Art
As the growth of number of wireless communication users, the co-channel fading, which degrades the transmission quality and limits the frequency efficiency, increases significantly. Traditionally, one resolution to overcome this problem is the incorporation of the smart antenna. In general, a smart antenna may refer to an adaptive antenna or a switched-beam antenna.
An adaptive antenna aims to reject the interference signals automatically by modifying its radiation pattern. However, it requires a complex RF circuit to synthesize the antenna steering beam. The other solution, i.e. the switched-beam antenna, only requires a set of switches to control the steering beam. Therefore, using the switched-beam antenna is much cost-effective.
The switched-beam antenna supporting WiFi 802.11b/g/n for an access point (AP) had been applied since several years ago. However, with the advance of wireless communication technology, the wireless communication devices may be configured with an increasing number of antennas. For example, a wireless local area network standard IEEE 802.11n supports multi-input multi-output (MIMO) communication technology, i.e. an wireless communication device is capable of concurrently receiving/transmitting wireless signals via multiple (or multiple sets of) antennas, to vastly increase system throughput and transmission distance without increasing system bandwidth or total transmission power expenditure, thereby effectively enhancing spectral efficiency and transmission rate for the wireless communication system, as well as improving communication quality.
As can be seen from the above, a prerequisite for implementing techniques, such as spatial multiplexing, beam forming, spatial diversity, pre-coding, etc., employed in the MIMO communication technology is to employ multiple sets of antenna to divide a space into many channels in order to provide multiple antenna field patterns. Therefore, it is a common goal in the industry to design antennas that suit both transmission demands, as well as dimension and functionality requirements.